By Nic Faulks, Feb 18 2018 09:11AM
Nic Faulks presented a talk on Bats in the Republic of Georgia. This was a different talk to last year’s which was more about survey methodology in forest areas, this talk presented the findings of a summer and winter survey of a limestone karst area, in central Georgia.
The main topic of the talk was horseshoe bats. In the UK we have two species, greater and letter horseshoe bat. The greater horseshoe bat (Rhinolophus ferrumequinum) emits calls which are between 69-83kHz, and generally at 83kHz. The lesser horseshoe bat (Rhinolophus hipposideros) emits calls which average about 110kHz, but calls can be lower, causing overlap with two other species (no present in the UK), The Mediterranean bat (Rhinolophus Euryale) and Mehelyi’s horseshoe bat (Rhinolophus mehelyi).
After the initial summer surveys, where two Anabat express units, located in two separate caves recorded 10, 000+ calls in 5 nights of recording, it was decided that further surveys were required. The summer data pointed to the presence of at least three species of horseshoe bat being present. In addition to which, one horseshoe seemed to be calling at around 92kHz…. Research on-online and conversations via email, confirmed that this was probably the less common, species Blasius’ horseshoe bat Rhinolophus blasii). But confirmation was needed.
Winter hibernation surveys were undertaken, by accessing the caves in and around the survey area. Supported by a Croatian bat expert Igor Pavlinic, who has handled all five species before, the surveyors went to find out what species were present, to photograph and confirm. After a week of searching caves and tunnels, we didn’t find any roosts of significance, maximum count was 7 bats in one cave (of three horseshoe species) but what we did do was confirm that the following species were present: Lesser and greater horseshoe - always roosting close to the cave/tunnel entrance - where ambient temperatures are cooler; Blasius and Mediterranian horseshoe bats – always found deeper in the cave/tunnel with an ambient temperature of 20c. In one tunnel we found a complete head skeleton of a bat. This was taken back to the Natural History Museum of Croatia, and confirmed to be that of the Balasius horseshoe bat; finally confirming, through skeletal remains, in the hand and by sonogram, that this species is present in Georgia.